1. Field of the Invention
This invention relates to a new type cam suitable for use in a parallel piston engine. More specifically the cam is adapted to fit into a circular arrangement of pistons and cylinders around a mainshaft, which pistons act in concert to effect rotation of the mainshaft by virtue of pressure exerted on the sinusoidal surface of the cam lobe encircling the mainshaft. Still more specifically the cam surface is specially designed to avoid friction and binding between the bearings and cam surface.
2. State of the Prior Art
Various types of engines for developing mechanical power, such as for propelling vehicles, have been proposed and are in use. The most commonly used is the internal combustion engine. However, in spite of their widespread use, there are a number of disadvantages in the types of engines used, namely, vibration, low efficiency, pollution, etc.
Vibration is generally due to the type of arrangement of the pistons with relation to the drive shaft, which in combination with poor timing, unequal power distribution, etc., is very inefficient in eliminating vibration although much has been done in absorbing vibration or otherwise eliminating its transmission to the passenger-riding portion of an automobile.
Since rotary engines may have pistons equally spaced around the mainshaft through which power is transmitted, it is conceivable that such engines might have less problems with vibration.
In U.S. patent application Ser. No. 920,459, the claims were rejected on the basis of Swiss Pat. No. 126,887 (1927) which shows a cam plate having been made from a plate fixed at a 45.degree. angle to the shaft 3 on which it is mounted by means of hub 2 as illustrated in FIG. 1 of the patent. The last sentence on page 1 of the patent refers to the "oval cam plate". FIGS. 36a, 36b and 36c illustrate the configuration of a circular plate 114 fixed at a 45.degree. angle to axle 115 by means of hub 116, the top and end views show the plate in oval or elliptical configuration. In fact the radius of the plate can be the hypotenus cc of an equilateral triangle having sides aa and bb of equal length. Therefore the dimensions of the oval plate can be calculated. For example, with a plate having a radius of 4 inches and the square of the hypotenus equal to the sum of the squares of the two sides this calculates to 4.sup.2 =(aa).sup.2 +(bb).sup.2, or since aa=bb,=2(aa).sup.2, and then 16=2(aa).sup.2 or 8=(aa).sup.2 and the length of aa and of bb equals .sqroot.8 or 2.828. The oval shape referred to in the Swiss patent is shown by the views in FIGS. 36a and 36c.
The only description in the Swiss patent for converting the plate as illustrated in present FIGS. 36a, 36b and 36c to the structure of the Swiss patent is in the third last paragraph prior to the claims for which the translation reads: "For the actual production of such precisely conforming contact surfaces it is possible to use, e.g., a lathe made according to FIG. 4. The raw molded cam plate is clamped by its shaft 3 between tailstock and headstock. On the draw spindle 14, a conical wheel 15 is firmly attached which engages a conical wheel 17, provided with a crankpin 16 and set into the lathe bed. The pin 16 engages a slit 19 of the support 18 on which the tool carrier 20 is attached by means of a separately driven, turning tool 21, the cutters of which are at a distance from their turning axis equal to the radius of the rollers, for which the contact surface to be made is designed. The transmission ratio between the shaft 3 and the conical wheel 17 is chosen such that both make the same number of rotations, or that per rotation of the shaft 3 there is one back and forth motion by the tool 21. In this manner the relative motion between the two parts, which occurs during the operation of the rollers on the finished cam plate, is fully copied, so that the tool produces the required distorted helicoidal surface along the edge of the plate. The processing of the two contact surfaces of the cam plate can suitably be done separately."
This description relates only to the conversion of the flat surface of the plate to the helicoidal surfaces 117 and 118 of the plate. Consequently the cam plate does not have the circular or cylindrical configuration of FIG. 3. Since no description of a method or an apparatus has been shown for converting the oval shape to a circular or cylindrical shape, we can only assume that the oval shape still exists. Just referring to it as a cylindrical shape does not change it from an oval to a circular or cylindrical shape.
More important is the fact that the cam plate described by the Swiss patent has only one rise and one reverse rise. The one rise is derived from that portion of the plate in FIG. 36b which extends above the axis of rotation and the reverse rise is derived from the opposite portion of the plate which extends below the axis of rotation. There is no way that a second rise or a second reverse rise could be derived from this plate. It cannot be argued, therefore, that it would be obvious to add a second rise and a second reverse rise. It is necessary to start with an entirely different structure and a different procedure to prepare the cam of applicant's invention.
A number of patents and other reference have been cited in parent and corresponding foreign applications. These include U.S. Pat. Nos. 1,197,896; 1,229,009; 1,351,365; 1,352,985; 1,487,338; 1,802,902; 1,867,504; 1,971,121; 2,027,076; 2,050,127; 2,237,621; 2,237,989; 2,243,817; 2,243,818; 2,243,819; 2,284,319; 2,966,899; 3,225,659; 3,374,695; 3,456,630; 3,726,183; and 4,090,478; British Pat. Nos. 251,607 (1926), 831,241 (1962) and 891,241; French Pat. Nos. 861,625(1939), 1,286,123 (1962) and 1,286,129 (1962); Swiss Pat. Nos. 58,995 (1911) and 126,887 (1927); and German Pat. Nos. 17,074 (1881) and 137,280 (1901); and Getriebtachnik by J. Vollmer, VEB Verlag Technik Berlin, pages 1-8 and 391-403. Some of these references describe engines in which pistons are arranged parallel to a mainshaft which is driven by a cam rotated by the action of the pistons. However none of these have met with commercial success. The lack of commercial success of the engines shown in these patents is believed to be due to a number of defects therein in which the designs do not provide for centerline thrust between the pistons, bearings and cam surface and the cam surfaces are not designed to avoid friction and binding between the bearings and the cam surfaces. Some of these references describe methods of making sinusiodal cams by tracing or duplicating a master cam. The difficulties and problems of making an original or master cam are described by above cited U.S. Pat. No. 3,726,183. The method of making an original or master sinusoidal cam is described in pages 693-710 of the 21st edition of "Machinery's Handbook" published 1981 by Industrial Press Company of 200 Madison Avenue, New York, N.Y. 10157. As will be noted this is a complicated, cumbersome method.